Bicycle multi-gear cassette

ABSTRACT

A bicycle multi-gear cassette mountable to a wheel hub driver mechanism that includes truncated conical shell having a first opening proximate a small shell base and a second opening proximate a large shell base. The openings are coaxial with an axis of the shell. A plurality of toothed sprockets having different numbers of teeth are disposed on the shell and extend radially of the central axis. A torque load transmitting profile is configured on the shell proximate one of the small and large shell bases. A radial load transmitting profile is configured on the shell proximate one of the small and large shell bases. The shell, sprockets, and the load transmitting profiles embody a single piece.

This application is a continuation application under 37 C.F.R. § 1.53(b)of U.S. patent application Ser. No. 11/689,466, filed Mar. 21, 2007, nowU.S. Pat. No. 9,150,280, which is hereby incorporated by reference inits entirety.

BACKGROUND OF THE INVENTION

The present invention relates to bicycle multi-gear cassettes, and moreparticularly, to a multi-gear cassette that includes a truncated conicalshell, a plurality of toothed sprockets disposed thereon, a torque loadtransmitting profile, and a radial load transmitting profile wherein theshell, sprockets and load transmitting profiles embody a single piece.

In a conventional multi-gear bicycle cassette, a plurality of discretesprockets of variable diameter are arranged radially about an axis of awheel hub. Each sprocket has a plurality of teeth spaced around itsperiphery for engaging a bicycle chain. The sprockets are mountable to ahub driver mechanism of the wheel hub to transfer pedaling forces fromthe bicycle chain to the wheel hub. In conventional designs, eachsprocket may include a torque and radial load transmitting profile thatmates to a corresponding profile on the hub driver mechanism. Onedisadvantage of this design is that the sprockets are actingindividually in transmitting pedaling load from the chain, at one end,to the hub driver mechanism, at the other end, making the sprocketsvulnerable to buckling and thus requiring thicker and heavier sprocketsthan desired.

In other devices, the individual sprockets may be attached to aplurality of carrier arms of an intermediate carrier, the arms receivingloading from the sprockets and transmitting it to the hub drivermechanism. Although the carrier may provide some lateral support to thesprockets, the carrier arms may themselves twist and flex under loading,also leading to buckling. Carriers with more rigid arms provideadditional buckling resistance but come with a weight penalty. Beyondbeing resistant to buckling, carrier and non carrier-based multi-gearcassettes must be sufficiently rigid to resist excessive twisting andflexing under high impact pedaling forces to provide positive and directload transmission to the wheel hub.

In the carrier cassettes described above, the discrete sprockets areattached to the carrier arms using bolts, mating threads, couplingprojections or the like. These mechanical connections not only requireadditional material on the mating pieces, making the sprocket assemblyheavier, but also introduce hole and thread features that weaken themating parts and provide possible fatigue and fracture failure points onboth the sprockets and carrier. Finally, such mechanical connectionsalso introduce additional unwanted flexibility as they twist and deformunder loading, softening load transmission from the chain to the hubdriver mechanism.

Accordingly, a single-piece cassette according to the present inventionavoids these design limitations by providing a rigid, buckling-resistantand lightweight load transmission path from the chain to the hub drivermechanism. In the prior devices having discrete sprockets, with orwithout intermediate carriers, the user may selectively replace one ormore of the individual sprockets to customize the gear ratios of thecassette. Additionally, in a cassette design with discrete sprockets,the complex recess and cutout features on the face of the sprockets, aswell as the precise chamfered tooth features, may be more readily andeconomically produced by stamping these features onto individualsprockets before assembly into a cassette. The present inventionachieves both a rigid and lightweight design that is contrary to theteachings of these prior devices. By using a single-piece truncatedhollow cone design that ignores the art-perceived need for discretesprockets, the present invention represents far more than a structuraldifference over these prior devices.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a lightweightsingle-piece multi-gear cassette that rigidly transmits load from thebicycle chain to the hub driver mechanism.

The present invention provides a bicycle multi-gear cassette thatgenerally includes a truncated conical shell, a plurality of toothedsprockets of variable diameter, a torque load transmitting profile, anda radial load transmitting profile wherein the shell, sprockets and loadtransmitting profiles embody a single piece. The sprockets are disposedon the shell and extend radially of the shell axis. The shell has afirst opening proximate a small shell base and a second openingproximate a large shell base. The first and second openings are coaxialwith an axis of the shell. A torque load transmitting profile isconfigured on the shell at the small shell base, at the large shellbase, or at an axially-interior location on the shell proximate thesmall or large bases, or any combination thereof. Likewise, a radialload transmitting profile is configured at the small shell base, at thelarge shell base, or at an axially-interior location on the shellproximate the small or large bases, or any combination thereof. Theradial and torque load transmitting profiles are positioned on the shellto stably support the cassette when mounted on the hub driver mechanism.

In one embodiment of the present invention, the shell may have a steppedconfiguration that includes a plurality of coaxial annular cylinders ofvariable diameter extending along the shell axis and a plurality ofcoaxial annular discs of variable diameter extending radially of theshell axis. The cylinders and discs are alternatingly arranged in astepped sequence. A torque load transmitting profile is configured at orproximate an axially-outermost cylinder or disc or any combinationthereof. Likewise, a radial load transmitting profile is configured ator proximate an axially-outermost cylinder or disc or any combinationthereof. The cylinders, discs, sprockets and load transmitting profilesembody a single piece.

In another embodiment of the present invention, the shell may have atapered configuration that includes a plurality of cone segmentsconnecting the toothed sprockets. One or more of the cone segments arepreferably oriented at an angle greater than 45 degrees from the shellaxis. The cone segments, sprockets and load transmitting profiles embodya single piece.

In another embodiment of the present invention, the bicycle multi-gearcassette may include a cap member that is coupled to or proximate thelarge shell base and extends radially of the shell axis. The cap memberincludes a first opening coaxial with the shell axis for receiving a hubdriver mechanism. The small shell base includes a second opening coaxialwith the shell axis for receiving the hub driver mechanism. The torqueload transmitting profile is configured at either the first or secondopenings, or both, for transmitting torque load to the hub drivermechanism. The radial load transmitting profile is configured at eitherthe first or second openings, or both, for transmitting radial load tothe hub driver mechanism.

These and other features and advantages of the present invention will bemore fully understood from the following description of one or moreembodiments of the invention, taken together with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a front perspective view of a bicycle multi-gear cassetteaccordance to one embodiment of the present invention;

FIG. 2 is a rear perspective view of the bicycle multi-gear cassette ofFIG. 1;

FIG. 3 is an exploded rear perspective view of the bicycle multi-gearcassette of FIG. 1 and a mating wheel hub;

FIG. 4a is an exploded cross-sectional view of the bicycle multi-gearcassette of FIG. 1;

FIG. 4b is an exploded cross-sectional view of an additional embodimentof the invention including a cap member attachable to interior portionof the shell;

FIG. 4c is a cross-sectional view of the bicycle multi-gear cassette ofFIG. 1;

FIG. 5 is an exploded cross-sectional view of an additional embodimentof a bicycle multi-gear cassette having a tapered shell;

FIG. 6 is a detailed cross-sectional view of a bicycle chain engaging asprocket tooth of the bicycle multi-gear cassette of FIG. 5; and

FIG. 7 is a detailed cross-sectional view of a bicycle chain engaging asprocket tooth of the bicycle multi-gear cassette of FIG. 1.

DETAILED DESCRIPTION

FIGS. 1-4 a and 7 illustrate a bicycle multi-gear or multi-sprocketcassette 10 according to one embodiment of the present invention. Thesprocket cassette 10 generally includes a shell 12, a plurality oftoothed sprockets 14, torque and radial load transmitting profiles 30,38, 46, wherein the shell 12, toothed sprockets 14 and load transmittingprofiles 30, 38, 46 embody a single piece. The single-piece constructionmay be achieved by any number of manufacturing processes, including forexample, forming, casting, forging, or machining. The toothed sprockets14 have different diameters and are disposed radially on the shell 12relative to the shell axis 18. Each sprocket 14 includes a plurality ofteeth 48 spaced around of the periphery of the sprocket 14 for engaginga bicycle chain 50 (FIGS. 6 and 7), each sprocket having a differentnumber of teeth.

In the embodiment shown, the shell 12 has a stepped configuration;however the shell may assume any linear or nonlinear shape that properlypositions the toothed sprockets. In the stepped embodiment shown, theshell 12 includes a plurality of coaxial annular cylinders 16 ofvariable diameter extending along a shell axis 18 and a plurality ofcoaxial annular discs 20 of variable diameter extending radially of theshell axis. The cylinders 16 and the discs 20 are alternatingly arrangedin a stepped sequence to form the conical shell 12.

The shell 12 further includes a first opening 22 at a small shell base24 and a second opening 26 at a large shell base 28. The first andsecond openings 22, 26 are coaxial with and substantially perpendicularto the shell axis 18. The shell 12 includes the torque and radial loadtransmitting profile 30 at the small shell base 24 on an inner surfaceof the shell 12 that engages a mating torque and radial transmittingprofile 32, in this embodiment mating projections, disposed on an outersurface on a hub driver mechanism 34 of a wheel hub 36. The torque andradial load transmitting profile 38 is also located at the large shellbase 28 on the inner surface of the shell that engages a mating loadtransmitting profile 40 on an outer surface of a removable cap member42. The cap member 42 extends radially of the shell axis 18. Inalternative embodiments, the cap member 42 may be coupled to a loadtransmitting profile disposed at an axially interior position of theshell 12 proximate the larger shell base 28 as shown in FIG. 4b . Inalternative embodiments, torque and radial load transmitting profilesneed not exist at both the large and small shell bases 24, 28, so longas at least one torque load transmitting profile and at least one radialload transmitting profile exist on the shell 12. In an alternativeembodiment, the cap member 42, shell 12, sprockets 14 and loadtransmitting profiles 30, 38, 46 may embody a single piece. The capmember 42 includes a third opening 44 for receiving the hub drivermechanism 34 therethrough. The cap member 42 further includes a torqueand radial load transmitting profile 46 at the third opening 44 on aninner surface of the cap member 42 that engages the mating torque andradial transmitting profile 32 on the hub driver body 34. Looking to thetorque and radial transmitting profile 46 of the cap member 42, radialsurfaces 41 transmit radial load to the hub driver mechanism 34, andtorque surfaces 43 transmit torque load to the hub driver mechanism 34.Torque and radial load transmitting profiles 30, 38 on the shell 12 havesimilar radial and torque surfaces. In an embodiment where only a radialload is being transmitted through the load transmitting profile, torquesurfaces 43 are eliminated.

In the embodiment of FIG. 5, a shell 52 includes a plurality of taperedcone segments 54 connecting the toothed sprockets 14 wherein the taperedcone segments 54, toothed sprockets 14 and load transmitting profiles30, 38, 46 embody a single piece. In a preferred embodiment, the taperedcone segments 54 form an angle θ greater than 45 degrees to provideincreased bending and buckling resistance to radially loading from thechain 50.

While this invention has been described by reference to particularembodiments, it should be understood that numerous changes could be madewithin the spirit and scope of the inventive concepts described.Accordingly, it is intended that the invention not be limited to thedisclosed embodiment, but that it have the full scope permitted by thelanguage of the following claims.

What is claimed:
 1. A bicycle multi-gear cassette mountable to a wheelhub, the cassette comprising: a truncated conical shell having a firstopening proximate a small shell base and a second opening proximate alarge shell base, the first opening proximate the small shell basereceiving the wheel hub; a plurality of toothed sprockets havingdifferent numbers of teeth disposed on the shell and extending radiallyof the central axis; a torque load transmitting profile configured onthe shell proximate one of the small and large shell bases; a firstradial load transmitting profile configured on the shell proximate thelarge shell base transmitting radial load to the wheel hub; a cap memberextending radially of the shell axis and non-rotatably coupled to theradial load transmitting profile proximate the large shell base, the capmember including a third opening and arranged proximate the large shellbase, the third opening also receiving the wheel hub; a second radialload transmitting profile configured at the third opening transmittingradial load to the wheel hub; and a third radial load transmittingprofile configured at the first opening and transmitting radial load tothe wheel hub, wherein the shell, sprockets, and the first and thirdload transmitting profiles are a single-piece construction, and whereinthe truncated conical shell comprises: a plurality of coaxial annularcylinders of variable diameter extending along an axis; a plurality ofcoaxial annular discs of variable diameter extending radially of theaxis; and the cylinders and discs alternatingly arranged in a steppedsequence.
 2. A bicycle multi-gear cassette according to claim 1, whereinthe cap member is discrete from the shell.
 3. A bicycle multi-gearcassette according to claim 2, wherein the torque load transmittingprofile is configured on the shell proximate the large shell base, thecap member further comprising: a second torque load transmitting profileconfigured at the third opening for transmitting torque load to thewheel hub.
 4. A bicycle multi-gear cassette according to claim 1,wherein the shell has a thickness smaller than a thickness of a base ofone of the plurality of sprockets.
 5. A bicycle multi-gear cassetteaccording to claim 1, wherein the wheel hub includes a hub drivermechanism.
 6. A bicycle multi-gear cassette according to claim 5,wherein the cap member is discrete from the shell.
 7. A bicyclemulti-gear cassette according to claim 6, wherein the torque loadtransmitting profile is configured on the shell proximate the largeshell base, the cap member further comprising: a second torque loadtransmitting profile configured at the third opening for transmittingtorque load to the hub driver mechanism.
 8. A bicycle multi-gearcassette according to claim 1, wherein the cap member extendssubstantially in a plane perpendicular to the central axis.
 9. A bicyclemulti-gear cassette according to claim 1, wherein the torque loadprofile is configured on the shell proximate the small base.
 10. Abicycle multi-gear cassette mountable to a wheel hub, the cassettecomprising: a truncated conical shell having a first opening proximate asmall shell base and a second opening proximate a large shell base, thefirst opening proximate the small shell base receiving the wheel hub,the truncated conical shell including: a plurality of coaxial annularcylinders of variable diameter extending along an axis, and a pluralityof coaxial annular discs of variable diameter extending radially of theaxis, the cylinders and discs alternatingly arranged in a steppedsequence; a plurality of toothed sprockets having different numbers ofteeth disposed on the shell and extending radially of the central axis;a torque load transmitting profile configured on the shell proximate oneof the small and large shell bases; a first radial load transmittingprofile configured on the shell proximate the large shell basetransmitting radial load to the wheel hub; a cap member extendingradially of the shell axis and non-rotatably disposed proximate thelarge shell base, the cap member including a third opening and disposedproximate the large shell base, the third opening receiving the wheelhub; a second radial load transmitting profile configured at the thirdopening transmitting radial load to the wheel hub; and a third radialload transmitting profile configured proximate the first opening andtransmitting radial load to the wheel hub, wherein the shell, sprockets,and the first and third load transmitting profiles are a single-piececonstruction, and wherein the truncated conical shell comprises: aplurality of coaxial annular cylinders of variable diameter extendingalong an axis; a plurality of coaxial annular discs of variable diameterextending radially of the axis; and the cylinders and discsalternatingly arranged in a stepped sequence.
 11. A bicycle multi-gearcassette according to claim 10, wherein the torque load transmittingprofile is configured on one of the discs and cylinders, and the firstradial load transmitting profile is configured on one of the discs andcylinders.
 12. A bicycle multi-gear cassette according to claim 10,wherein one of the plurality of annular cylinders has a thicknesssmaller than a thickness of a base of an adjoining sprocket and one ofthe plurality of annular discs has a thickness smaller than thethickness of the base of the adjoining sprocket.
 13. A bicyclemulti-gear cassette mountable to a wheel hub, the cassette comprising: atruncated conical shell having a first opening proximate a small shellbase and a second opening proximate a large shell base; a cap memberextending radially of the shell axis coupled to the large shell base fortransmitting load therebetween; a plurality of toothed sprockets ofvariable diameter disposed on the shell and extending radially of theaxis, the cap member including a third opening coaxial with the shellaxis for receiving the wheel hub, the first opening coaxial with theaxis for receiving the wheel hub; a torque load transmitting profileconfigured at one of the first and third openings for transmittingtorque load to the wheel hub; and a radial load transmitting profileconfigured at one of the first and third openings for transmittingradial load to the wheel hub, wherein the shell, sprockets and loadtransmitting profiles are a single-piece construction, and wherein thetruncated conical shell comprises: a plurality of coaxial annularcylinders of variable diameter extending along an axis; a plurality ofcoaxial annular discs of variable diameter extending radially of theaxis; and the cylinders and discs alternatingly arranged in a steppedsequence.
 14. A bicycle multi-gear cassette mountable to a wheel hub,the cassette comprising: truncated conical shell means having a firstopening proximate a small shell base and a second opening proximate alarge shell base, the first opening proximate the small shell basereceiving the wheel hub; a plurality of toothed sprockets havingdifferent numbers of teeth disposed on the truncated conical shell meansand extending radially of the central axis; torque load transmittingmeans configured on the truncated conical shell means proximate one ofthe small and large shell bases; and first radial load transmittingmeans configured on the truncated conical shell means proximate thelarge shell base transmitting radial load to the wheel hub; cap membermeans extending radially of the central axis and non-rotatably coupledto the radial load transmitting means proximate the large shell base,the cap member means including a third opening and arranged proximatethe large shell base, the third opening receiving the wheel hub, secondradial load transmitting means configured at the third openingtransmitting radial load to the wheel hub; and third radial loadtransmitting means configured at the first opening and transmittingradial load to the wheel hub, wherein the truncated conical shell means,sprockets, and the first and third load transmitting means are asingle-piece construction, and wherein the truncated conical shell meanscomprises: a plurality of coaxial annular cylinders of variable diameterextending along an axis; a plurality of coaxial annular discs ofvariable diameter extending radially of the axis; and the cylinders anddiscs alternatingly arranged in a stepped sequence.
 15. A bicyclemulti-gear cassette according to claim 14, wherein the cap member meansis discrete from the truncated conical shell means.
 16. A bicyclemulti-gear cassette according to claim 15, wherein the torquetransmitting means is configured on the shell proximate the large shellbase, the cap member means further comprising: second torque loadtransmitting means configured at the third opening for transmittingtorque load to the wheel hub.